Steam generator



June 16', 1942. w. F. KEENAN, JR, ETAL 2,286,

STEAM GENERATOR Filed April 29, 1938 NVENTORS WALTER F/(EENAMIQ, JY/MT/Nf'k/SCH.

Patented June 16, 1942 STEAM GENERATOR Walter Keenan, .Ir., PelhamManor, and Martin Frisch, New York, N. Y., assignors to Foster WheelerCorporation, New York, N. Y.

a corporation of New York I Application April 29, 1938, Serial No.204,944 7 Claims. (Cl. 122-459) This invention relates to steamgenerators and particularly pertains to the purification of the steamgenerated therein. More particularly, it is the object of the inventionto provide an improved steam washer for removing solids which ordinarilyare entrained by the steam generated in the boiler, by washing thesaturated steam released in the boiler with fresh feed water ofrelatively low solid concentration- Subsequently the steam so purifiedmay be dried by suitable means before it leaves the boiler. A furtherobject of the invention is to provide a novel and effective steam dryingdevice.

For a clear understanding ofthe special features and advantages thatcharacterise the invention, reference may be had to the followingdescription considered in connection with the accompanying drawingforming a part thereof and in which:

Fig. 1 is a longitudinal vertical sectional view, illustrating more orless diagrammatically, a boiler steam and water drum within which isdisposed washing and drying devices embodying the preferred form of theinvention, taken substantially on line i-l of Fig. 2, and

Fig. 2 is an enlarged transverse sectional view taken substantially online 2-2 of Fig. 1.

Referring to the drawing, reference character it designates a steam andwater drum of a steam generator of suitable construction. A plurality oftubes I I connected to the lower por tion of the drum, represent boilercirculating and steam generating tubes. A group of steam circulators I 2communicate with the steam space of the drum, while a plurality ofoutlet tubes l3 are provided to conduct steam from the drum to asuperheater, not shown. Fresh feed water is supplied to the generatorthrough feed pipe it which enters the drum at one end thereof andextends horizontally for the greater part of The length of the drum at alevel well below the normal water line therein. The feed pipe I4 isadequately supported and secured in the drum by brackets 5 and U-boltsIS.

The steam washer in the form shown, comzle 20 and is provided with anupstanding flange specific forms of trays may be employed so long as thenozzles 20 or their equivalent are proprises a series of parallel bubbletrays I! which I extend transversely to the longitudinal axis of thedrum and are supported above the water line therein by bracket membersl8 and l 9, the former of which are also arranged to preventthe steamfrom by-passing the trays. The assembly of these vided. Covering each ofthese nozzles is an inverted light metal cap 2|, the sides and ends ofwhich, in the embodiment selected for illustration, are cut away toprovide raised edge portions 22 which are serrated as shown. Theseserrated edge portions 22 are normally under the level of a body offresh feed water which is maintained in the trays, and the dimensions ofthe serrations may be varied to provide the desired degree ofsub-division of the streams of steam flowing through the nozzles 20 andunder the caps 2| as hereinafter described. Also the sides and ends ofthe caps 2| need not, in all instances, be cut away to provide theraised edge portions illustrated, in which event, the serrations willextend upwardly from the lowermost edges of the caps.

Saturated steam released in the drum [I enters the nozzles 20 in thetrays I! of the washer, and after passing upwardly through the nozzlesis reversed in direction of flow by the caps 2| and flows downwardlythrough the fresh feed water on the trays and under the serrations, andthere- I after flows upwardly through the water between adjacent caps,and escapes into the steam space above the washer assembly. Theserrations along the sides of the caps 2| provide means whereby thesteam is divided into a great number of uniformly distributed smallstreams of steam. Fresh feed water is constantly supplied to the traysat one end thereof by a plurality of feed connections 23 that conductall the fresh feed water from the feed pipe It to the trays. The waterfrom connections 23 flows across the trays around and between thenozzles 29 to overflow connections 24 through which the water flows intofeed pan 25 located in thelower portion of the drum at one side thereofand. under the normal water level in the drum. The height of the overflow connections 24 determines the level of the fresh feed watermaintained on the trays. An inclined baille 26, which extends from theupper wall of the drum to the feed water inlet side of the trayassembly, directs the steam that enters the drum through the steamcirculators l2 downwardly to the steam space between the water line inthe drum and the trays. From this steam space, all the steam released inthe drum enters the nozzles, and by its passage through the fresh feedwater as already described, any entrained boiler water of highconcentration is washed out and replaced by feed water of much lowerconcentration.

The steam after leaving the washer passes through a steam drier 21consisting in the form shown, of spaced groups of parallel vertical wiremesh screens 28' which remove such moisture from the steam that has notalready been eliminated by gravit in the upper steam space between thetrays and the drier. As illustrated, two groups of screens are utilizedwith three spaced screens in each group. The groups. are disposed sothat the steam passes through thegroups-and enters a dry steam space 34between the twogroups. Preferably, adjacent screens in each group are sodisposed that the individual wires of adjacent screens are arranged instaggered relationship with respect to the path of steam flowtherethrough. The moisture removed from the steam by the drier collectson the drip pan 29, which is positioned immediately beneath the screens28, and directs the wet steam through the screens 28. This moisture isreturned to the body of water in the drum by drain pipes 30- and 3| atopposite ends of the drier. -The dry steam leaves the drum through theoutlet tubes l3 and is conducted thereby to a superheater, not shown.The drier assembly is supported from the shell of drum It! by angleplates 35 and 36 which are welded to the drum shell. These plates 35 and36 also prevent the wet steam from bypassing the drier. End plates 32and 33 which extend from the inner surface of the upper portion of thedrum wall to a point below the bottom of the trays H support and enclosethe washer and drier assemblies. The washer and drier are arrangedand-supported in such manner that all the steam released in the boilermust pass through the washer and the drier screens before leaving theboiler.

Steam washers embodying the invention are effective with such low steamvelocities that the entrainment of fresh feed water by the steam leavingthe washer is very low and therefore comparatively little work remainsfor the steam drier in the. elimination of excessive entrained moisture.The pressure drop through the washer and through the drier is also verylow so that internal drainage of, washer and drier presents nodifiiculty.

Thefeed pan 25 into which the trays I! drain through pipes 24, may beused for phosphate or other chemical injection when such treatment isused for conditioning the boiler water internally.

The steam nozzles 20 in the trays ll may be of suitable form other thanthe elongated rectangular form illustrated. For example, the nozzles maybe circular, oval, or square in transversecross-sectional configuration.The caps 2| for the steam nozzles will, in general, conform to theparticular nozzle arrangement utilized.

Although the washer and the drier are disclosed as being disposed in asteam and water drum of a boiler, it will be understood that the washeror the drier or both, may be located outside of the steam and Waterdrum. For example, the washer may be disposed in a separate drum orother enclosure to which feed water is initially supplied and from whichit is delivered to the boiler circulation.

It will be understood that the embodiments of the invention disclosedherein are preferred forms, and that modifications may be made tnerelnwithout departing from theprinciples of the invention, which accordinglyis not to be limited excepting by the scope of the appended claims.

What is claimed is:

1. In a steam and water drum for a water tube steam boiler, steamintakes in the upper portion of said drum, partitioning means forming anupper chamber in said drum above the normal water level therein, oneside of said partition being adjacent said steam intakes and positionedto direct steam passing therethrough downwardly. a steam washerpositioned in the drum comprising a bubble tray forming the bottom ofsaid partitioning means, said tray having a plurality of steam nozzlestherein, bubble caps for said nozzles, means-for-delivering boiler feedwater to said tray, said means extending below said tray and beingconnected to one side thereof, and means for maintaining feed water at apredetermined level on said tray below the upper ends of said nozzlesand for delivering said water to'the lower portion of said drum.

2. In a steam andwater drum for awater tube steam boiler, steam intakesin the upper portion of said drum, partitioning means forming an upperchamber in said drum above the normal water level therein, one sideofsaidpartition being adjacent said steam intakes and positioned to directsteam passing therethrough downwardly, a steam washer positioned-in thedrumcomprising a plurality of bubble trays extending transversely of thelongitudinal axis of said drum and forming the bottom of saidpartitioning means, each tray having a steam nozzle therein, a bubblecapfor each of said nozzles; means for delivering boiler feed waterextending below said trays, a conduit from said boiler feed-waterdelivering means to one side of each tray, and means for maintainingfeedwater at a predeterminedlevel on said-trays below the upper ends ofsaid nozzles and; for deliveringsaid, water to the lower portion ofsaiddrum;

3. In a steam and water drum for awater tube steam boiler, steamintakesin the upper portion of said drum, partitioningmeans forming anupper chamber in said drum above the normal water leveltherein, onesideof saidpartition beingadjacent said steam intakes and positioned'todirect steam passing therethrough downwardly, a steam washer positionedin the drum comprising a bubble tray forming the bottom of saidpartitioning means, said tray having a plurality of steam nozzlestherein, bubble caps for said nozzles, means for delivering boiler feedwater to said tray, said means extending below said tray and beingconnected to one side thereof, a feed pan positioned in the lowerportion of the drum, and means for maintaining feed'water at apredetermined level on saidtray below. the upper ends of said nozzlesand'for delivering said water to said'feed pan.

4., In a steam and water drum for a watertube steam boiler, steamintakesin. the upper portion of said drum, partitioning. means forming an upperchamber in said. drum above the normal water level therein, one side ofsaid partition being adjacent said steam intakes and positioned todirect steam passing therethrough downwardly, a steam washer positionedin the drum comprising a bubble tray forming the bottom of saidpartitioning means, said tray having a plurality of steam nozzlestherein, bubble caps for, said nozzles, means for delivering boiler feedwater to said tray, said means extending below said tray and beingconnected to one side thereof, afeed pan positioned in the lower portionof the drum, means for maintaining feed water at a predetermined levelon said tray below the upper ends of said nozzles, and means forconducting liquid from the tray to said feed pan.

5. In a steam and Water drum for a water tube steam boiler, steamintakes in the upper portion of said drum, partitioning means forming anupper chamber in said drum above the normal water level therein, oneside of said partition being adjacent said steam intakes and so inclinedupwardly to the wall of said drum as to direct steam from said intakesdownwardly, a steam washer positioned in the drum comprising a bubbletray forming the bottom of said partitioning means, said tray having aplurality of steam nozzles therein, bubble caps for said nozzles, meansfor delivering boiler feed water to said tray, said means extendingbelow said tray and being connected to one side thereof, and means formaintaining feed water at a predetermined level on said tray below theupper ends of said nozzles and for delivering said water to the lowerportion of said drum.

6. In a steam and water drum for a water tube steam boiler, steamintakes in the upper portion of said drum, partitioning means forming anupper chamber in said drum above the normal water level therein, oneside of said partition being adjacent said steam intakes and positionedto direct steam passing therethrough downwardly, a steam washerpositioned in the drum comprising a bubble tray forming the bottom ofsaid partitioning means, said tray having a plurality of steam nozzlestherein, bubble caps for said nozzles, means for delivering boiler feedwater to said tray, and means for maintaining feed water at apredetermined level on said tray below the upper ends of said nozzlesandfor delivering said water to the lower portion of said drum.

7. In a steam and water drum for a water tube steam boiler, steamintakes in the upper portion of said drum, partitioning means forming anupper chamber in said drum above the normal water level therein, oneside of said partition being adjacent said steam intakes and positionedto direct steam passing therethrough downwardly, a steam washerpositioned in the drum comprising a bubble tray forming the bottom ofsaid partitioning means, said tray having a plurality of steam nozzlestherein, bubble caps for said nozzles having means for dividing thestreams of steam which have passed through said nozzles into arelatively large number of substantially uniformly distributed smallstreams of steam, means for delivering boiler feed water to said tray,said means extending below said tray and being connected to one sidethereof, and means for maintaining feed water at a predetermined levelon said tray below the upper ends of said nozzles and for deliveringsaid water to the lower portion of said drum.

WALTER F. KEENAN, JR. MARTIN FRISCH.

